1. Field of the Invention
The present invention relates generally to coating tools, and more particularly, to a shafting structure for a coating tool adapted to transfer to a target object a paste, correcting paint or the like, which is adhered to the surface of a transfer tape.
2. Related Art
conventional coating tools are known which perform a coating operation by transferring a paste or a correcting paint adhered to the surface of a transfer tape, to a target object. Such conventional coating tools typically include supply and take-up reel gears which mesh with one another, and supply and take-up reels which are mounted on the same shaft as the supply or take-up reel gear, respectively, for integral rotation therewith relative to the corresponding mounting shaft. A problem which may occur with coating tools of this general type is that the transfer tape may break or be cut when unused transfer tape is drawn out with a suitably strong tensile force so that only the supply reel rotates and an excessive degree of stress is applied to the transfer tape. In order to overcome this problem the supply reel and the supply reel gear of conventional coating tools have typically been made integral with each other in such a manner that the supply reel gear is held clamped by an elastic edging strip formed on the inner wall surface of the engagement hole of the supply reel, whereby the supply reel rotates idly with respect to the supply reel gear when the tensile force applied to the transfer tape overcomes the frictional force exerted between the supply reel and supply reel gear.
When the unused transfer tape is drawn out with a strong tensile force, the supply reel and the supply reel gear begin to rotate integrally and when the rotational speed exceeds a predetermined value, such that the frictional force generated between the supply reel and the supply reel gear via the elastic edging strip disposed therebetween is overcome, the supply reel does not rotate integrally with the supply reel gear. Instead the supply reel rotates idly with respect to the supply reel gear. Consequently, the supply reel gear stops rotating while the unused transfer tape is drawn out. Furthermore, the take-up reel gear, which meshes with the supply reel gear, and the take-up reel which is mounted on the same shaft as the take-up reel gear, also do not rotate. Accordingly, no excessive degree of stress is applied on the transfer tape delivered from the supply reel, thereby preventing such inconvenience as the breakage or cutting of the transfer tape.
However, such conventional coating tools of the type previously described are subject to the following disadvantage. Since the elastic edging strip formed on the inner peripheral wall surface of the engagement hole of the supply reel, for the purpose of causing the supply reel and the supply reel gear to rotate integrally with one another, is made of a thin or soft material making it elastic, the edging strip may become deformed when it is stored, transported or used in a high-temperature environment for a prolonged period of time. More particularly, the elastic edging strip may become deformed in such a manner that it expands outwardly and fails to hold the cylindrical top portion of the supply reel gear securely so that sometimes the phenomenon of idling takes place between the supply reel and the supply reel gear, thereby preventing the supply reel and the supply reel gear from rotating integrally with one another. The foregoing idling between the supply reel and the supply reel gear due to deformation of the elastic edging strip is undesirable and sometimes causes the transfer tape to be tangled inside and outside of the main body of the coating tool or may also result in an overflow of excess transfer tape accumulating outside the main body of the coating tool since the take-up reel is unable to take up the waste tape passing over the printer head of the coating tool. This is the case since the take-up reel gear meshes with the supply reel gear and the take-up reel is integral with the take-up reel gear.
Thus, what is meant by the above-described disadvantage is that in the case of the take-up reel which is integral with the take-up reel gear meshing with the supply reel gear and adapted to take up the transfer tape which has become unavailable or wasted due to its passage over the printer head, it is not possible to take up the waste tape to a length corresponding to the length of the unused transfer tape due to the idle rotation of the supply reel with respect to the supply reel gear and consequently, there sometimes takes place such inconvenience as the entanglement of the transfer tape inside and outside the main body of the coating tool or the overflowing of the transfer tape from the main body of the coating tool.
The present invention is provided as a solution to the previously discussed problems associated with conventional coating tools. An object of the present invention is to provide a coating tool which is simple in structure and is capable of performing the delivery and take-up of transfer tape smoothly and accurately. This is accomplished in such a manner that a supply reel, a take-up reel, a supply reel gear and a take-up reel gear are arranged within the body of the tool so as to allow the supply reel to rotate integrally with the supply reel gear, and to allow the takeup reel to rotate integrally with the take-up reel gear. Furthermore, the coating tool of the present invention prevents the idle rotation of the supply reel with respect to the supply reel gear due to the thermal deformation of the component parts of the coating tool, thereby overcoming the previously discussed problem with conventional coating tools. Additionally, the coating tool of the present invention does permit the idle rotation of the supply reel relative to the supply reel gear when an excessive tensile force is applied to the correction tape, with idle rotation of the supply reel being desirable in this instance so as to prevent the breakage or cutting of the transfer tape.
In order to achieve the foregoing advantages, the coating tool according to one embodiment of the present invention comprises a main body having a printer head projecting outwardly from an opening formed at the top end thereof. The main body of the coating tool receives a supply reel therein, with the supply reel including an engagement hole supported by a supply reel shaft and being adapted to deliver an unused transfer tape having a paste or a correcting paint applied thereon, to the printer head. A supply reel gear having a cylindrical portion is mounted on the same shaft as the supply reel, so as to rotate integrally with the supply reel. The coating tool further includes a take-up reel having an engagement hole supported by a take-up reel shaft and being adapted to take up the transfer tape after use. A take-up reel gear having a cylindrical portion is supported by the same shaft as the take-up reel so as to rotate integrally with the take-up reel. An annular rib is formed on the outer peripheral surface of the cylindrical portion of the supply reel gear or the take-up reel gear so as to surround the cylindrical portion of the corresponding gear. An elastic edging strip is formed on a lower portion of the inner wall surface of the engagement hole of the supply reel or the take-up reel so as to fit between the annular rib and the outer peripheral wall of the cylindrical portion of either the supply reel gear or the take-up reel gear, depending upon the configuration of the coating tool.
The elastic edging strip is formed peripherally on the bottom end of the inner wall surface of the engagement hole of the supply reel so as to hold and engage the cylindrical portion of the supply reel gear, thereby allowing the supply reel to interlock with the supply reel gear. The elastic edging strip is made small in thickness or of a soft material so as to have a sufficient degree of elasticity so that even when the elastic edging strip tends to become deformed by expanding outward, the thermal deformation of the elastic edging strip is prevented since the elastic edging strip fits between the cylindrical portion of the supply reel or the take-up reel and the annular rib formed to surround the cylindrical portion of the supply reel gear or the take-up reel gear. Accordingly, the holding and engagement of the cylindrical portion of the supply reel gear or the take-up reel gear by the elastic edging strip is secured, thereby preventing the idle rotation of the supply reel or the take-up reel with respect to the supply reel gear or the take-up reel gear, respectively. Consequently, the supply reel or the take-up reel and the supply reel gear or the take-up reel gear are made rotatable integrally with each other thereby allowing the delivery and taking-up of the transfer tape to be performed securely.